Police in the US state of Alabama have rescued a five-year-old child who was being held captive in an underground bunker.

FBI agents stormed the bunker where 65-year-old Jimmy Dykes was holed up with the boy.

The siege had lasted seven days, since Dykes had shot a school bus driver and taken the child as he fled.

“Mr Dykes was observed holding a gun. At this point FBI agents fearing the child was in imminent danger entered the bunker and rescued the child. The child appears physically unharmed and is being treated in a local hospital. The subject is deceased.” said FBI agent Steve Richardson.

Negotiations with Dykes, a retired trucker and Vietnam veteran, had deteriorated over the last 24 hours.

The youngster, identified only as Ethan, is being treated at a local hospital but is said to be physically unharmed. Officials had previously thanked Dykes for allowing deliveries of medication and toys to the boy, who it is thought he took at random.

The hostage-taking comes amid heightened concerns in the US about gun violence and school safety.